1. Field of the Invention
The present invention relates to a newly constructed on-line drying control method for powdered or granular materials including inorganic materials such as resin and ceramic and to an on-line drying control system for such materials, wherein materials stored and dried in a drying means such as a hopper dryer are automatically sampled and quickly measured for their moisture content, and the temperature of the drying means is controlled based on the obtained result.
2. Prior Art
Generally, keeping the moisture content materials constant has presented a most important problem to maintain good quality of the resin products because an inappropriate moisture content of the resin materials to be supplied into a molding machine causes defects in the products, such as a silver line or a void. Therefore, resin materials are usually dried by the use of a hopper dryer before being supplied into the molding machine.
However, resin materials are apt to absorb moisture in the air before being fed into the hopper dryer while stored in a silo or a tank of intermediate stage for a fixed period of time after a kraft bag or a flexible container which is used to carry resin materials is opened. Accordingly a fixed heating temperature and a fixed heating time are set for the hopper dryer based on an estimated moisture content of the resin materials. But such a conventional method for drying resin materials by the use of a hopper dryer leaves further room for improvement in saving labor to achieve the most appropriate drying method as the heating of materials is controlled based on an estimation without sufficiently understanding the conditions of the resin materials before heated.